Both horizontal and vertical axis Archimedes screw plants for separating slurry are well known, for example, in the treatment of livestock effluents.
Regarding a traditional vertical axis Archimedes screw separation plant, it comprises the following elements:                a slurry feeding device towards a tubular sifting device;        a vertical axis slurry feeding device inside which are housed advancing and pushing means, adapted to move and compress the slurry, and means adapted for filtering the slurry in transit;        an evacuating device for the liquid slurry fraction after its separation from the solid fraction, separation substantially occurring inside said the tubular sieve;        an evacuating device (19, 22) for the substantially dry separated solid after its separation from the liquid fraction, separation substantially occurring inside the tubular sieve as a result of flattening the slurry against the sifting wall and the filtering action of the holes on the sieve itself.        
However, the vertical axis Archimedes screw separation plants on the market today present the following drawbacks:                efficient separation between the liquid and the solid phase of the slurry cannot be obtained;        sorts of “bridges” are formed between the filter wall and the slurry pushing means consisting of solid material clogging the sieve resulting in a loss of filtering surface; due to the abovementioned “bridges” and agglomerations formed within the sieve the plant must be frequently stopped causing significant economic losses to the manager and/or owner thereof, and        there is not a regular and consistent supply of the slurry towards the tubular sifting device.        